In a multi-processor (MP) architecture, multiple processors are present in the same system. Associated with the system are a specific set of power and thermal requirements. Known power limiting strategies include powering down a CPU functional unit, e.g., a floating-point unit or an on-die cache, or trading off speed for reduced power consumption in a hard drive. Tight power budgets and thermal restrictions may also limit the maximum frequency at which the processors in a multi-processor system are run. Thus, the optimal performance and capacity of the processors is limited. Specifically, these requirements put a limit on the amount of power that can be consumed by the processors.
Though MP systems provide many advantages, several engineering challenges arise when using MP systems. Among these challenges is the challenge of designing and operating a system such that sufficient heat is dissipated in the system. To address heat dissipation challenges, MP systems are designed within an underlying power and thermal envelope. For example, when a chassis that hosts a MP system has a limited amount of airflow available to cool the processors (i.e., when the system can only dissipate a limited amount of heat), then the chassis is designed for a limited amount of power consumption and an associated limited performance of the processors.
Prior solutions included running the processors at a sub-optimal performance level to meet the overall chassis power and thermal cooling budget, adding fans and extra control circuitry, limiting the number of I/O cards, or other useful features in the system, and reducing the power budget available for other features in the system.